Yes. Earlier this month, Instapundit Reynolds was pushing that bogus story about NASA discovering an alien life form living in Mono Lake. The space cadets claimed they had found a microbe that survived on arsenic when in reality it was a common bacterium that had adjusted (evolved?) to life in the high level arsenic environment of Mono Lake by replacing some of the phosphorus molecules with the related arsenic molecule in its DNA. If it hadn't, it would have starved to death. Not only that, but NASA had artificially increased the arsenic level when they force fed arsenic to the little beasties in the lab which required the otherwise quite normal bacterium to replace even more phosphorous with arsenic to survive.